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Published on 6 January 2021


Low-cost, miniaturized ultrasound emitters/receivers

   What is Pmut?

  • CEA-Leti has designed low-cost, miniaturized Piezoelectric, Micromachined Ultrasound Transducers (PMUTs) capable of operating at different frequencies.

  • PMUT technology coordinates MEMS ultrasound emission and reception components on silicon; these are composed of suspended membranes that can be put into motion by piezoelectric actuators. The actuator structure is made up of thin layers of piezoelectric materials (AlN or PZT) activated by electrodes positioned either side to form a sandwich.

  • Conversely, the electrodes collect charges when the component operates in sensor mode. A beamforming method allows greater component functionality, especially when the emission or reception signal is scanned.


  Applications:

  • PMUTs emit ultrasounds up to 3 - 5 m in air. They are also very efficient as emitters/receptors in a liquid medium. PMUT technology is intended for highly varied applications in the medical, consumer or car automotive domain.

  • Its first, already available, commercial applications include fingerprint detection, medical imaging ultrasonography and presence detection, while home automation and virtual reality feature among its targeted future markets.


   What's new:

Compared with standard, ceramic piezoelectric transducers, silicon-based MEMS transducers:
  • Allow low-cost fabrication of 2D or 3D matrices
  • Allow greater miniaturization: 2 to 10 times smaller depending on required performance
  • Can achieve a broad range of ultrasound frequencies (1 kHz to 30 MHz depending on size)
  • Provide greater bandwidth, while allowing adjustment of the transducer's mid-range frequency
  • Provide an overall reduction in transducer based on standard manufacturing processes. 


  What's next:

A more complex electronic system is being finalized; this will enable beamforming to widen the component emission angle for detection of obstructions or objects in invisible areas.
  •       FICHE

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    (341 Ko)


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PUBLICATIONS

AlN-based bimorph piezoelectric
micromachined ultrasound
transducer for air-borne
application below 100 kHz
J.Jung, J-C.Bastien, R.Dejaeger,
A.Lefevre, O.Ndjoye-Kogou,
F.Blard and B.Fain, MUT 2019

Wafer-level experimental study
of residual stress in AlN-based
bimorph piezoelectric micromachined
ultrasonic transducer
J.Jung, J-C.Bastien, A.Lefevre,
K.Benedetto, R.Dejaeger, F.Blard
and B.Fain, 2020 Eng. Res. Express
2 045013